R-AECHE-17

Bonding:

• Three distant substances:

  • Na(s) - Metallic (metal only)
  • NaCl (s) - Ionic (metal and non-metal)
  • Cl_2 (g) - Covalent (non-metal only)

• Metalloids can have both metallic and non-metal properties.

• In metallic bonding, valence electrons become delocalised.

• Delocalised vs localised: Delocalised means the electron doesn't belong to any atom. It becomes mobile. Localised means it is part of a local atom.

Properties of Metals:

• Chemical Properties:
  • Reactivity
    1. Consider electronic configuration, position on periodic table etc.
• Physical properties (focus on this):
  • melting point
  • boiling point
  • density
  • electrical and thermal conductivity
  • malleability
  • ductile

Metallic Bonding:

• Why is the melting point of metals high?

  • Note - all metals are solid except mercury

• Melting point means you have particles that are closer together that are separated into a looser arrangements where particles are further apart. i.e. Solid -> liquid.

• Any type of bonding is electrostatic force of attraction (for this section, wait till you get to intermolecular forces L)

• e.g. in Metallic bonding, there is a stronger electrostatic attraction between cations of metal and the sea of delocalised electrons in a network, if the metal has a higher melting point.

• When describing melting point, write about heat energy required.

• Solid -> liquid is ions, liquid -> gas is atoms.

It takes more energy to separate ions of metal if you have a higher melting point. This is due to a stronger electrostatic attraction between ions of metals and the sea of delocalised electrons in a network.

• Liquid metals also conduct electricity, so liquid metals still have a sea of delocalised electrons.

Melting point

• Why do some metals have high melting points, and why do other have lower ones?
• Aluminium has a significantly higher melting point.
• Aluminium's electronic configuration: $2,8,3$.
  • Thus, each atom of aluminium has 3 electrons it can delocalise.
• Therefore, in a diagram, cations have a charge of 3+, and there are more electrons than sodium.
• Thus, there is a stronger electrostatic attraction between cations and the sea of delocalised electrons.
• This logic follows for density. - Low charge = low density

Electrical conductivity:

• In metals, electrons conduct electricity. Specifically, the delocalised ones(because they are mobile).
• Gasses on its own are not electrically conductive.

Malleability:

• The ability for metal to be bent into shapes
• If you apply force in a metallic network, you do not break the structure.
• The sea of delocalised electrons are non-directional. Thus, when you apply force cations slide around in a sea of delocalised electrons.
• The structure does not break, as the structure is rigid.

Ductility:

• Quality of metals that allows metals to be pulled into wires.
• When producing a wire, the cations just move into a linear shape, surrounded by the sea of delocalised electrons in a network.

Ionic Bonding:

• If a compound has a metal and a non-metal, it is ionic.

• Typical behaviour: solid at room temperature.

• Noble gases are chemically stable because they have full outer shells of electrons.

• s-block elements lose one or more electrons to form stable cations (positively charged ions).

• There is a transfer of electrons from metal atoms to non-metal atoms to form anions and cations with stable electronic configurations.

• p-block elements gain one or more electrons to form stable anions (negatively charged ions).

• There is a transfer of electrons from metal atoms to non-metal atoms to form anions and cations with stable electronic configurations.

yea ms pilling is the kind of teacher to teach an entire chem topic in a single lesson

Note: Most metals are found on the left side. As discussed previously in the Periodicity section, elements on the left have a lower ionisation(first + others) energy. This is essential as there must be little energy required to ionise metal atoms to produce cations and a sea of delocalised electrons

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